Change search
Refine search result
1 - 42 of 42
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Auenmüller, Christoph
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Automated Controller Design for a Missile Using Convex Optimization2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The focus of the present master thesis is the automation of an existing controllerdesign for a missile using two aerodynamic actuating systems. The motivation isto evaluate more missile concepts in a shorter period of time.The option used is trimming and linearization of a highly nonlinear missile at specic conditions. According to these conditions, either a two-dimensional operatingpoint grid dened by Mach number and height or three-dimensional operatingpoint grid dened by Mach number, height and angle of attack is generated forthe whole operating range of the missile. The controllers are designed at thesepoints using convex optimization. The convex set denes the pole placement areawhich is constrained by linear matrix inequalities according to the dynamic behaviorof the missile at the operating point conditions. These controllers describea validity area where the missile can be stabilized. This area consists all neighboringoperating points and denes therefore the grid density which can dier atspecic regions of the operating range. Controlling the missile to the target makesit necessary to apply gain-scheduling in order to get the manipulated variable byinterpolation of adjacent operating points. During this blending of the controllersa problem called windup can occur when an actuator is saturated. This mightlead to instability in worst case but can be counteracted by a model-recovery antiwindupnetwork which guarantees stability in the presence of saturation. Thisanti-windup design is automated by an ane linear parameter dependency of thegrid parameters and has the same validity area like the controllers.The whole design was successfully developed and tested in MATLAB/Simulink onmissiles using one or two aerodynamic actuating systems. The controllers have agood performance at small and high acceleration steps and the anti-windup keepsthe missile stable even though the actuators are saturated. Stability and robustnessof the controllers and anti-windup networks was veried as well as an airdefense maneuver where the missile starts at the ground and intercepts a targetat high altitude was successfully simulated for dierent grids and missiles.

  • 2.
    Avasak, Kalyani
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Institute of Space Systems, University of Stuttgart.
    Mission Analysis and Trajectory optimisation for project CAPE2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Atmospheric reentry is a challenging part of human space ight and planetary entry missions.At the Institute of Space Systems in University of Stuttgart the idea of projectCAPE was conceived in 2012. Project Cubesat Atmospheric Probe for Education aimsto demonstrate the capability of miniaturised technologies of the micro electric plasmathruster, reentry vehicle design and ablative shielding material developed in this institute.The mission scenario is such that the CAPE is being deployed from the InternationalSpace Station and needs to complete the de-orbit of the Service and deorbit module andre-entry of the Atmospheric entry module in less than 1 year. The Cube satellite weighs3.0 kg consisting of a 2+1 unit service design module with solar panels, pulsed plasmapropulsion system of the university of Stuttgart (PETRUS) and a micro atmosphericreentry module (MIRKA-2). This reentry vehicle is unique in its size and weighs 0.5kg. During its reentry phase, it will be subjected to the intense aero-thermal loads at theThermal Protection System front which are absorbed by its ablative heat shield. But thecharacteristics of the re-entry trajectory like the ight path angle, entry velocity and entrypoint greatly determine the survivability against the integral heat load for this ballisticreentry vehicle. Although the success of the mission is considerably higher when having acontrolled reentry, in case of ballistic vehicles it is solely determined by the mission design.The main task is to investigate and develop the optimal re-entry trajectories in thedesign-time phase of mission development for MIRKA-2 vehicle that satises the objectiveof minimizing heat loads and adhering to operational constraints. Thus, the aimof this thesis is to provide a novel solution and optimum trajectory of the de-orbit andre-entry ight to maximize the survivability of the reentry module. The con icting parametersin this mission would be the operational limit of the pulsed plasma thruster andminimum heat loads during reentry ight. The simulation of these trajectories is carriedout in MATLAB using the REENT software developed in the Institute of Space Systems,University of Stuttgart. Its source code is composed in Fortran 77 which is integratedinto MATLAB. A careful mission analysis with the constraints of the capacity of pulsedplasma thruster, impulse provided by the separation mechanism and survivability of thereentry vehicle is carried out to prove the feasibility of this mission. In order to accomplishthe survivability during re-entry the aspects that have been modelled are the ight dynamicsof the satellite, aerodynamic and aero-thermal loads, spacecraft behaviour underthe external loads and local heating process.

  • 3.
    Baker, Niklas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Feasibility and design of miniaturized Control Moment Gyroscope for a 3-axis stabilized Micro Satellite2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, a feasibility study will be conducted in order to determine if the usage of acontrol moment gyroscope is a possibility for a micro satellite as its attitude control. Thegoal is to conclude if gyroscopes are suitable replacements for the current reaction wheelswhich are acting as the attitude control for the satellite. In the first part of the thesis thegeneral function of the control moment gyroscope and three different types of arrangementsare displayed with all their respective advantages and disadvantages. Then one ofthem will be designed to fit within the restrictions of 1U. The full design of the pyramidconfiguration was chosen due to its compact size and spherical angular momentum envelope.The full design contains all the components such as motors, flywheels, mounts,frame, screws etc. which provide a cost estimate which is a huge input in determiningthe feasibility of this thesis. In the future the manufacture of the pyramid configurablecontrol moment gyroscopes shall be tested in the future with a more advanced steeringlaw in order to determine the full potential of the attitude control system.

  • 4.
    Berčič, Laura
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Swedish Institute of Space Physics.
    Instrumental and environmental effects on RPC-ICA measurements of the cometary ion dynamics at comet 67P/CG2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Observations provided from RPC-ICA in combination with the data from RPC-MAG and ROSINA-COPS show that many aspects of the time variability of the detected ions is correlated with the magnetic field or -- to a smaller extent -- with neutral atmosphere density. We also show that not all changes in the cometary ion data reflect the nature of the plasma dynamics, but are a consequence of the instrumental limitations. The main outcome of the article in Appendix 1 is that the cometary ions can be divided into two populations with distinct characteristics. One population we termed the convecting population, is accelerated to higher energies through the interaction with the solar wind. The other population we termed the expanding population is moving radially away from the nucleus in the terminator plane. Both populations exhibit a significant anti-sunward component.In addition we present in this thesis a case with observations day-side of the terminator plane. There we show how the expanding population has a sunward component, consistent with initial radial expansion of the ions from the nucleus which gradually turn into an anti-sunward flow which is then observed in the terminator plane.

  • 5.
    Bethge, Matthias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Situation and Threat Comprehensionand Conduit of Action with particular reference to aFuture Technology Data Fusion System2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 6.
    Bhattacharya, Shaondip
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Multi-agent System Distributed Sensor Fusion Algorithms2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The concept of consensus filters for sensor fusion is not an entirely new proposition but one with an internally implemented Bayesian fusion is. This work documents a novel state update algorithm for sensor fusion which works using the principle of Bayesian fusion of data with variance implemented on a single integrator consensus algorithm. Comparative demonstrations of how consensus over a pinning network is reached are presented along with a weighted Bayesian Luenberger type observer and a ’Consensus on estimates’ algorithm. This type of a filter is something that is novel and has not been encountered in previous literature related to this topic to the best of our knowledge. In this work, we also extend the proof for a distributed Luenberger type observer design to include the case where the network being considered is a strongly connected digraph.

  • 7.
    Blanco, Enrique
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    DESIGN OF A SCALABLE, ADAPTABLE AND RELIABLE DEORBITING MECHANISM2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 8.
    Dikmen, Serkan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Development of Star Tracker Attitude and Position Determination System for Spacecraft Maneuvering and Docking Facility2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Attitude and position determination systems in satellites are absolutely necessary to keep the desired trajectory. A very accurate, reliable and most used sensor for attitude determination is the star tracker, which orient itself in space by observing and comparing star constellations with known star patterns. For on earth tests of movements and docking maneuvers of spacecrafts, the new Spacecraft Maneuvering and Docking (SMD) facility at the chair of Aerospace Information Technology at the University of Würzburg has been built. Air bearing systems on the space ve- hicles help to create micro gravity environment on a smooth surface and simulate an artificial space-like surrounding. A new star tracker based optical sensor for indoor application need to be developed in order to get the attitude and position of the vehicles. The main objective of this thesis is to research on feasible star tracking algorithms for the SMD facility first and later to implement a star detection software framework with new developed voting methods to give the star tracker system its fully autonomous function of attitude determination and position tracking. Furthermore, together with image processing techniques, the software framework is embedded into a controller board. This thesis proposes also a wireless network system for the facility, where all the devices on the vehicles can uniquely communicate within the same network and a devel- opment of a ground station to monitor the star tracker process has also been introduced. Multiple test results with different scenarios on position tracking and attitude determination, discussions and suggestions on improvements complete the entire thesis work. 

  • 9.
    Dillibabu, Surender
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Design,Analysis, and prototype of underwater glider2016Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
  • 10.
    Flores Garcia, Erick
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Simulation of attitude and orbital disturbances acting on ASPECT satellite in the vicinity of the binary asteroid Didymos2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Asteroid missions are gaining interest from the scientific community and many new missions are planned. The Didymos binary asteroid is a Near-Earth Object and the target of the Asteroid Impact and Deflection Assessment (AIDA). This joint mission, developed by NASA and ESA, brings the possibility to build one of the first CubeSats for deep space missions: the ASPECT satellite. Navigation systems of a deep space satellite di er greatly from the common planetary missions. Orbital environment close to an asteroid requires a case-by-case analysis. In order to develop the Attitude Determination Control System (ADCS) for the mission, one needs detailed information about orbital disturbances in the vicinity of the asteroid.

    This work focuses on the development of a simulator that characterises the orbital disturbances a ecting the ASPECT satellite in the space environment near the Didymos asteroid. In this work, a model of orbital conditions and disturbances near the Didymos system was defined. The model integrates several classical and modern models of spacecraft motion and disturbance. An existing Low Earth Orbit (LEO) simulator was modified and updated accordingly to the ASPECT mission scenario. The developed simulator can be used to analyse the disturbances to be counteracted by the ADCS of the ASPECT satellite. The objective of the study was to quantify the e ect of both non-gravitational and gravitational disturbances. The simulator was used to analyse di erent orbit scenarios related to the period of the mission and to the relative distance between the spacecraft and the asteroid system. In every scenario, the solar radiation pressure was found to be the strongest of the disturbance forces. With the developed simulator, suitable spacecraft configurations and control systems can be chosen to mitigate the e ect of the disturbances on the attitude and orbit of the ASPECT satellite. 

  • 11.
    Forsberg, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Providing Air Traffic Control Services for Small Unmanned Aircraft Through LTE2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 12.
    Garcia Hernandez, Juan Camilo
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Development of a Class D motor amplifier for a next-generation mechanism control electronics2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis was written at Airbus DS GmbH in Friedrichshafen, Germany, as part of a project which aims to develop a new generation of class-D power amplification circuits for sinusoidal commutating motors controlling the movement of different mechanisms in satellites. Currently used topologies have disadvantages such as high power loss, analog controlling and high degree of signal distortion.

    This work first simulates available topologies which were previously developed by the company in order to compare them and build a trade-off list so the most suitable circuit is selected. Then, by further simulating and analysis several improvements to the circuit are suggested and a final schematic is developed including an analogue-to-digital converter and a total of three phases to power a motor. After a demonstrator circuit was designed and built, it was tested by using an external real time target machine to generate the corresponding PWM signals in correspondence to a controlling signal generated via Simulink.

    The final product of this thesis confirmed the simulation results such as an improved signal quality at higher frequencies in comparison to an available measurement from a previous generation circuit. The flexibility of the topology as well as the possibility of implementing a digital control was also confirmed during this phase of the project. Upon further work, the dimensioning of the output low pass filter should be improved and a digital PID controller should be implemented in the controlling FPGA.

    NOTE: This version of the Master Thesis deviates from the formal original  submitted for examination in order not to disclose confidential information of Airbus DS GmbH. All positions in the document, where additional information was removed are properly identified. This document can be published according to the general rules of the Julius-Maximilians-Universität Würzburg and the Lulea University of Technology.

  • 13.
    Grosse, Christian
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Development of a Star Camera Algorithm for Calculating thePosition on Earth and Mars (VaMEx DLR)2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Within the scope of the Valles Marineris Explorer mission of the German Aerospace Center(DLR), the position of a ground vehicle on Mars needs to be determined. Due to the fact thatMars has no global magnetic field and no positioning system like Earth, a facility independentsystem is necessary. In this context, a star camera based positioning system shall be developed.The subject of this thesis is the development, implementation and verification of a star camerabased transformation algorithm for calculating the latitudinal and longitudinal position on Mars.In addition, an Earth based transformation algorithm is developed, implemented and evaluated fortesting purposes, that is for testing the hardware for the mission under real conditions on Earth.The thesis gives an insight into the fundamental theory of transformation algorithms commonlyused for the transformation between celestial and planet coordinate systems. A self-developedtransformation algorithm is presented which is able to transform a tilted star vector in TopocentricHorizon Coordinate System into observer longitude and latitude position. Moreover, themodular implementation in MATrix LABoratory (MATLAB) and Realtime Onboard DependableOperating System (RODOS) is described in detail. In the further course of the thesis the results ofdifferent test scenarios are outlined and evaluated. The overall results are eventually discussed regardingtheir implications for the mission and subsequently, suggestions for further improvementof the algorithm are made.

  • 14.
    Guldevall, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Development of an FPGA based Trigger for Slow Moving Events for the EUSO-TA Telescope2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 15.
    Güttler, Johannes
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Field-Site Prototype for HABIT (FSP-HABIT): Characterizing Martian Salts Prior to the ExoMars 2020 Mission2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    One of the major remaining question about Mars is its habitability - if the requirements necessary to allow for life are presently fulfilled. One of the most relevant ingredients for life, as we know it, is water. Indirect evidence of transient liquid water on Mars has been retrieved from both rover [Martín-Torres et al., 2015] and orbiter [Ojha et al., 2015].

    [Martín-Torres et al., 2015] inferred the existence of an active water cycle, driven by chlorate and perchlorate salts, which are commonly found on the Martian surface, and absorb atmospheric water to form stable hydrated compounds and liquid solutions. This happens through a process called deliquescence (absorption of moisture from the atmosphere by the salts and dissolving into a liquid solution). One of the goals of HABIT is to confirm the hypothesis about the water cycle on Mars. HABIT will record the behavior of a selection of salts on Mars, and will also record Martian environmental conditions (UVdose, air and ground temperatures).

    The Field-Site Prototype for HABIT (FSP-HABIT) was the first prototype of HABIT deployed during field-site campaigns. Three campaigns took place during summer 2016: First, a short preparatory campaign in Abisko, Sweden, was carried out. The second campaign took place in Iceland, within the EU COST Action TD1308 ORIGINS (Origins and evolution of life on Earth and in the Universe), and the third campaign was conducted within the NASA Spaceward Bound India Program in Ladakh. After providing the corresponding background on the mission framework and the scientific background, this document covers the mechanical, electrical, and software design of the instrument. Afterwards, the steps taken to test the instrument and their results are covered, followed by a rating of the instrument and ideas for future improvements. Instruments like FSP-HABIT will enable the characterization of hygroscopic salts by their conductivity as liquid brines are good conductors, hydrated salts are poor conductors, and dehydrated salts are insulators. During the field-site campaigns, the measurements of FSP-HABIT were used to characterize the near surface environment by its temperature, pressure and relative humidity. Now, these measurements are available for comparison with microbiological studies of the water, ice and soils to characterize the habitability of the explored site. The lessons learned while designing and building FSP-HABIT can be used to inform the development of further prototypes for space missions such as HABIT.

  • 16.
    Hagen, Christoph
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    A Bluetooth based intra-satellite communication system2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis presents a wireless communication system for intra-satellite communication based on Bluetooth Low Energy technology, which can have many benefits regarding the design and operation of satellites. The proposed design based on the nRF53832 chip from Nordic Semiconductor is described, followed by the results of several tests regarding the most important design criteria for its application in small satellites. The tested aspects include the power consumption of the wireless module in different operation modes, which is sufficiently low for the application even in small satellites. Signal strength measurements for various output power settings and obstacles show that reliable communication is possible in a satellite mockup. No packet error was detected, and latencies of less than 30 ms combined with achievable data rates between 200 and 700 kbps should be sufficient for most CubeSat satellites. Additionally, details are given to successfully integrate the chip with existing satellite subsystems. A code library is provided to simplify the communication between the modules, and a concept of a redundant system is established to increase the reliability for critical satellite subsystems. The overall assessment of the technology suggests that the presented system is suitable for in-orbit deployment with the Aalto-3 satellite (currently being developed at Aalto University), which will provide further validation of the technology. 

  • 17.
    Hagos, Tesfamichael Marikos
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Aalto University .
    Estimation of phases for compliant motion: Auto-regressive HMM, multi-class logistic regression, Learning from Demonstration (LfD), Gradient descent optimization,2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    The full text will be freely available from 2018-01-01 08:00
  • 18.
    Hammarsten, Michael
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    A statistical study of incoherent scatter plasma line enhancements during the International Polar Year ’07-’08 in Svalbard2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There was a large radar campaign during 2007 and 2008, the International Polar Year (IPY),and at that time the EISCAT Svalbard Radar was operated and measured the ionosphere continuouslyat most times. This report presents statistical results from an electron enhancementpoint of view. Until now there has been some research into the field and results based on theions in the ionosphere, and the enhancements we refer to as Naturally enhanced ion acousticlines (NEIALs). Plasma line data from May 2007 to February 2008 has been analysed inorder to find and classify enhancements as NEIALs have been classified but with respect tothe electron distribution instead of the ion distribution. A method of detection was developedin order to differentiate the enhancements from the background with a relation between theminimum and maximum power of each measured dump. Results show that there is a largedifference between the downshifted plasma lines and the upshifted plasma lines, both has arange distribution peak at 180 km and the upshifted plasma line has another peak at 230 kmwhich the downshifted plasma line does not. The occurrence rate of the enhancements was1.64 % for the downshifted plasma line and 4.69 % for the upshifted plasma line. Threedifferent types of enhancements are classified using the variance distribution for the peakfrequency of that detected dump, Single, Profile, and Diffuse. The Single enhancements havea bit different spectral, range, and time of day distributions than of the Profile and Diffusedistributions. The Diffuse classifications are mostly wrong classifications and aliasing and itis very similar to Profile enhancements as seen by its distribution.

  • 19.
    Hirschmüller, Korbinian
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Development and Evaluation of a 3D Point Cloud Based Attitude Determination System2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 20.
    Ishtiaq, Shehryar
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Optimization of a Laser Coarse Pointing Assembly for Low Earth Orbit Satellite Missions2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A laser communications terminal was developed by the Deutsches Zentrum für Luft- und Raumfahrt and is already being flown over the BIROS satellite, however it is desired to improvepointing performance with the utilization of a coarse pointing assembly. This study presents theseries of optimizations towards space applicability performed on an existing coarse pointingassembly for such a laser communications terminal. This module was initially built for airborneapplications and tested upon the tornado aircraft. The idea was to use this existing flight performanceproven system and with the help of commercial off the shelf components providebetter structural stability and tolerance to the Low Earth Orbit space environment. Criticalpoints were highlighted and the scope of the study was defined to provide reliable modal andthermal analysis results for its performance under the specified mission design parameters. Acircular low earth orbit of 450 km altitude with an inclination similar to that of the BIROS satellitewas chosen to simulate the space environmental effects for this analysis. A preliminary designreview highlighted the need to increase the link budget, which brought down the beamdivergence to 50 μrad from a previous 100 μrad. This made the entire system sensitive andmore susceptible to environmental factors requiring a more rigid and deformation tolerantstructure. In this study the effect of thermal loadings in worst-case scenarios were analysed.Aside from the optimization changes, the results of the analysis pointed out the need to utilizethermal control measures for optimum performance. Therefore, some passive thermal controlmeasures are also presented in this study, which are necessary to meet the requirements.

  • 21.
    Johansson, Mattias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Evaluation of Sensor Solutions & Motor Speed Control Methods for BLDCM/PMSM in Aerospace Applications2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The goal of this thesis was to evaluate sensors and motor speed control methods for BLDC/PMSM motors in Aerospace applications. The sensors and methods were evaluated by considering accuracy, robustness, cost, development gain and parameter sensitivity. The sensors and methods chosen to simulate were digital Hall sensors and sensorless control of BLDC motors. Using Matlab Simulink/Simscape some motor speed control methods and motor speed estimation methods were simulated using the Hall sensors and sensorless control as a basis. It was found that the sensorless control methods for BLDC motors couldn't estimate the speed accurately during dynamic loads and that the most robust and accurate solution based on the simulations was using the digital Hall sensors for both speed estimation and commutation and this was tested on a hardware setup.

  • 22.
    Kettig, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Benchmarking of C++ image processing libraries within the Euclid project2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this report, the issue of selecting a C++ image processing library for the Euclid science ground segment (SGS) is tackled. A new benchmark is proposed to objectively compare libraries according to both static, development-related, and dynamic, execution-related criteria.

    Instead of comparing isolated functions, a much more realistic scenario is implemented: a complete processing pipeline based on a use-case algorithm, called L.A. cosmic. Already existing in the SGS and used multiple times for the flagging of galactic cosmic rays (GCRs), this algorithm is the optimal choice for setting up the benchmark. This makes the results much more usable than with classical single- function benchmarks.

    First, the used tools as well as both categories are explained with their respective criteria listed, all tailored to the needs of the SGS. This also introduces the statistical profiling used throughout the project. Additionally, a scientific validation is introduced that monitors the accuracy of the implementations created.

    Afterwards, the benchmark is conducted and the results are presented and discussed. Indeed, including static criteria helps taking into account development and debugging time – key elements of the project life. Moreover, most library contenders are lacking important functions required for the implementation of the reference algorithm and are therefore excluded from further measurements. Documenting the missing or unclear functions gives then an overview about how user-friendly a library is to develop with.

    The scientific validation depicts that a missing function in one of the contenders and the resulting deviation from the reference results in a lower accuracy. Leaving out the problematic part of the pipeline improves the results, yet only with a higher amount of stars being misinterpreted as GCRs.

    The dynamic criteria report that all contenders perform better than a python reference version as well as a consistent linear dependency to the input image size, while also offering an approach to multi-core processing. Yet, the latter exhibits problems of some libraries to scale appropriately with more resources, leaving the results divided between the single- and multi-core setups for this benchmark.

    When taking this parameter of cores into account, the benchmark allows to recommend the most appropriate library to the SGS. 

  • 23.
    Kiewiet, Luca
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Université Toulouse III Paul Sabatier.
    Design of the Hold-Down and Release System for the Concur™ Solar Array Wing2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    The full text will be freely available from 2018-12-31 08:00
  • 24.
    Kindberg, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Development of a miniature Gridded ion thruster2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 25.
    Kohlbacher, Anton
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Development of a Novel Relative Localization Sensor2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    By enabling coordinated task execution and movement, robotic swarms can achieve efficient exploration or disaster site management. When utilizing Ultra-wideband (UWB) radio technology for ranging, the proposed relative localization sensor can be made lightweight and relatively indifferent to the ambient environment. Infrastructure dependency is eliminated by making the whole sensor fit on a swarm agent, while allowing for a certain amount of positional error. In this thesis, a novel algorithm is implemented in to constrained hardware and compared to a more traditional trilateration approach. Both algorithms utilize Particle Swarm Optimization (PSO) to be more robust towards noise and achieves similar accuracy, but the proposed algorithm can run up to ten times faster. The antenna array which forms the localization sensor weighs only 56g, and achieves around 0.5m RMSE with a 10Hz update rate. Experiments show that the accuracy can be further improved if the rotational bias observed in the UWB devices are compensated for.

  • 26.
    Kudaravalli, Venkata Narayana Chowdary
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Design and fabrication of test-bed for testing attitude determination of spin stablilized spacecraft.2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

     Attitude determination for a spin stabilized satellite is calibrated. A mock spacecraft and a spin simulation test bed are designed and developed. Spin simulation testbed which provides position data is used to acquire true position data. The data from the simulator test bed is used as reference for the sensor data to estimate the error in position of sensor data. Two vector method attitude solutions are used here for attaining the estimated position. Two vectors used for attitude determination are magnetic field vector and sun sensor vector. Calibration of accuracy for sensors is main goal, which is attained by calculating error by comparing the estimated position with true position.

  • 27.
    Kunicka, Beata Iwona
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Spacecraft dynamic analysis and correlation with test results: Shock environment analysis of LISA Pathfinder at VESTA test bed2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The particular study case in this thesis is the shock test performed on the LISA Pathfinder satellite conducted in a laboratory environment on a dedicated test bed: Vega Shock Test Apparatus (VESTA). This test is considered fully representative to study shock levels produced by fairing jettisoning event at Vega Launcher Vehicle, which induces high shock loads towards the satellite.

    In the frame of this thesis, some transient response analyses have been conducted in MSC Nastran, and a shock simulation tool for the VESTA test configuration has been developed. The simulation tool is based on Nastran Direct Transient Response Analysis solver (SOL 109), and is representative of the upper composite of Vega with the LISA Pathfinder coupled to it. Post-processing routines of transient response signals were conducted in Dynaworks which served to calculate Shock Response Spectra (SRS).

    The simulation tool is a model of forcing function parameters for transient analysis which adequately correlates with the shock real test data, in order to understand how the effect of shock generated by the launcher is seen in the satellite and its sub-systems. Since available computation resources are limited the parameters for analysis were optimised for computation time, file size, memory capacity,  and model complexity. The forcing function represents a release of the HSS clamp band which is responsible for fairing jettisoning, thus the parameters which were studied are mostly concerning the modelling of this event. Among many investigated, those which visibly improved SRS correlation are radial forcing function shape, implementation of axial impulse, clamp band loading geometry and refined loading scheme. Integration time step duration and analysis duration were also studied and found to improve correlation.  From each analysis, the qualifying shock environment was then derived by linear scaling in proportion of the applied preload, and considering a qualification margin of 3dB.

    Consecutive tracking of structural responses along shock propagation path exposed gradual changes in responses pattern and revealed an important property that a breathing mode (n = 0) at the base of a conical Adapter translates into an axial input to the spacecraft. The parametrisation itself was based on responses registered at interfaces located in near-field (where the clamp band is located and forcing function is applied) and medium-field with respect to the shock event location. Following shock propagation path, the final step was the analysis of shock responses inside the satellite located in a far-field region, which still revealed a very good correlation of results. Thus, it can be said that parametrisation process was adequate, and the developed shock simulation tool can be qualified. However, due to the nature of shock, the tool cannot fully replace VESTA laboratory test, but can support shock assessment process and preparation to such test.

    In the last part of the thesis, the implementation of some finite element model improvements is investigated. Majority of the panels in spacecraft interior exhibited shock over-prediction due to finite element model limitation. Equipment units modelled as lump masses rigidly attached with RBE2 elements to the panel surface are a source of such local over-predictions. Thus, some of the units were remodelled and transient responses were reinvestigated. It was found that remodelling with either solid elements, or lump mass connected to RBE3 element and reinforced by RBE2 element, can significantly improve local transient responses. This conclusion is in line with conclusions found in ECSS Shock Handbook.

  • 28.
    Lidström, Viktor
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Mass Loading of Space Plasmas2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The solar wind interaction with an icy comet is studied through a model problem. A hybrid simulation is done of a box with evenly distributed water ions and protons, where initially the water ions are stationary, and protons move with the speed of the solar wind. The purpose of the thesis is to investigate the interaction between the two species through the convective electric field, and focus is on early acceleration of pick-up ions, and deflection of the solar wind. It is relevant to the cometary case, because it enables study of the physics of this interaction, without involving other mechanisms, such as bow shock, magnetic field pile-up and draping. The species are found to exchange kinetic energy similar to a damped oscillator, where the dampening is caused by kinetic energy being transferred to the magnetic field. At early times, i.e. times smaller than the gyration time for the water ions, the solar wind does not lose much speed when it is deflected. For comparable number densities, the solar wind can be deflected more than 90° at early times, and loses more speed, and water ions are picked up faster. The total kinetic energy of the system decreases when energy builds up in the magnetic field. The nature of the energy exchange is strongly dependent on the number density ratio between water ions and protons. A density instability with behaviour similar to a plasma beam instability forms as energy in the magnetic field increases, and limits the amount of time the simulation preserves total energy, for the particular hybrid solver used. There is a discussion on the structure of the density instability, and it is compared to cometary simulations.

  • 29.
    Mannes, Quentin
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    ICE Cubes Mission: Design, Development and Documentation of the Cube-Zero System2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The International Space Station provides a high-quality of microgravity and extended exposure time which makes it a platform of choice for microgravity research. In order to increase accessibility of onboard experimentation, Space Applications Services will soon launch the ICE Cubes facility as part of its ICE Cubes Service. The facility is foreseen to host standardized plug-and-play payload cubes to reduce overall cost and procedure time required to install payloads on the station. To remotely support the facility it is decided to develop a utility cube named Cube-Zero that will be launched and installed with the facility on the station. This thesis work included the complete design, development and documentation of the cube.

    The thesis started by conducting a preliminary needs and market study from which two specific purposes were defined for the cube. In addition to its original function of support-utility, the cube is tasked to be a technical commercial demonstrator for the service. This led to the conceptual design of the cube as a multidisciplinary framework able to host two user-defined experiment modules. The preliminary concept was further refined in this paper and with support of prototypes, simulations and analyses led to a final functional design for the Cube-Zero.

    The work is concluded with the manufacturing of an engineering model of the cube. The model is fully operational, can support the test of the facility before launch and can demonstrate to users its versatility and ease of use in operating any kind of experiment module.

    Eventually, the information gathered in this thesis report will support future users into developing their own Cube-Zero payload module and guide Space Applications Services into manufacturing, testing and operating the Cube-Zero protoflight model.

  • 30.
    Martell, Angel Alfredo
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Benchmarking structure from motion algorithms with video footage taken from a drone against laser-scanner generated 3D models2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Structure from motion is a novel approach to generate 3D models of objects and structures. The dataset simply consists of a series of images of an object taken from different positions. The ease of the data acquisition and the wide array of available algorithms makes the technique easily accessible. The structure from motion method identifies features in all the images from the dataset, like edges with gradients in multiple directions, and tries to match these features between all the images and then computing the relative motion that the camera was subject to between any pair of images. It builds a 3D model with the correlated features. It then creates a 3D point cloud with colour information of the scanned object. There are different implementations of the structure from motion method that use different approaches to solve the feature-correlation problem between the images from the data set, different methods for detecting the features and different alternatives for sparse reconstruction and dense reconstruction as well. These differences influence variations in the final output across distinct algorithms.

    This thesis benchmarked these different algorithms in accuracy and processing time. For this purpose, a terrestrial 3D laser scanner was used to scan structures and buildings to generate a ground truth reference to which the structure from motion algorithms were compared. Then a video feed from a drone with a built-in camera was captured when flying around the structure or building to generate the input for the structure from motion algorithms. Different structures are considered taking into account how rich or poor in features they are, since this impacts the result of the structure from motion algorithms. The structure from motion algorithms generated 3D point clouds, which then are analysed with a tool like CloudCompare to benchmark how similar it is to the laser scanner generated data, and the runtime was recorded for comparing it across all algorithms. Subjective analysis has also been made, such as how easy to use the algorithm is and how complete the produced model looks in comparison to the others.

    In the comparison it was found that there is no absolute best algorithm, since every algorithm highlights in different aspects. There are algorithms that are able to generate a model very fast, managing to scale the execution time linearly in function of the size of their input, but at the expense of accuracy. There are also algorithms that take a long time for dense reconstruction, but generate almost complete models even in the presence of featureless surfaces, like COLMAP modified PatchMacht algorithm. The structure from motion methods are able to generate models with an accuracy of up to \unit[3]{cm} when scanning a simple building, where Visual Structure from Motion and Open Multi-View Environment ranked among the most accurate. It is worth highlighting that the error in accuracy grows as the complexity of the scene increases. Finally, it was found that the structure from motion method cannot reconstruct correctly structures with reflective surfaces, as well as repetitive patterns when the images are taken from mid to close range, as the produced errors can be as high as \unit[1]{m} on a large structure.

  • 31.
    Nazarious, Miracle Israel
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Design, Development and Characterization of a Digital Sun Sensor prototype for Nano Satellite Applications2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sun sensors serve as eyes of satellites. It is one of the basic components in satellites used for the purpose of determining the position of the sun in order to properly orient the solar arrays. The technological challenge involved in such sensors is to find the right balance between the field-of-view and the accuracy characteristics. For every sun sensor, there is a trade-off between these two performance parameters which has to be optimized for the expected performance requirements. Developing a low-weight, low-power sun sensorfor nano-satellite applications managing better performance in terms of field-of-view and accuracy is the challenge, this project has accepted to address.

    The true motivation behind this project was to develop an advanced solar-powered, bluetooth enabled digital sun sensor entitled as Multihead Autonomous Wireless Digital Sun Sensor (MAWDSS). To reach this ambitious goal, the footpath to be followed includes developing a prototype of a digital sun sensor and an autonomous wireless digitalsun sensor leading to the final product.

    This thesis work lays the first step and proposes a design of a digital sun sensor using low-cost commercial-off-the-shelf (COTS) components, develop a prototype and conduct performance characterization to compare with a commercial benchmarking sun sensor.The desired performance requirements were predefined prior to describing the detailed design aspects of the sun sensor. The problems encountered during experimental testing and the recommended suggestions to overcome them are presented.

    This thesis defines a complete product development life cycle involving skills from all three aspects of engineering: mechanical, electrical and programming. Each individual regime of the project are properly addressed with relevant figures and plots in separate chapters for the ease of following the report.

  • 32.
    Pope, Charles
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Calibration and Uncertainty Analysis of a Spacecraft Attitude Determination Test Stand2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Experimental testing of attitude determination systems still plays an important role, despite increasing use of simulations. Testing provides a means to numerically quantify system performance, give confidence in the models and methods, and also discover and compensate for unexpected behaviours and interactions with the attitude determination system. The usefulness of the test results is dependent on an understanding of the uncertainties that contribute to the attitude error. With this understanding, the significance of the results can be assessed, and efforts to reduce attitude errors can be directed appropriately. The work of this thesis is to gain a quantitative understanding of the uncertainties that impact the attitude error of low cost spinning spacecraft using COTS camera (as Sun sensor) and MEMS magnetometer. The sensors were calibrated and the uncertainties in these calibrations were quantified, then propagated through the Triad method to uncertainties in the attitude. It was found that most systematic errors were reduced to negligible levels, except those due to timing latencies. Attitude errors achieved in the laboratory with the experimental setup were around 0.14 degrees (3σ) using either the Triad, q-method or Extended Kalman Filter with a gyro for dynamic model replacement. The errors in laboratory were dominated by magnetometer noise. Furthermore, correlated systematic errors had the effect of reducing the attitude error calculated in the laboratory. For an equivalent Sun-mag geometry in orbit, simulation showed that total attitude error would be of the order of 0.77 degrees (3σ). An uncertainty contribution analysis revealed this error was dominated by uncertainties in the inertial magnetic field model. Uncertainties in knowledge of the inertial Sun model, sensor calibration, sensor alignment and sensor noise were shown to be insignificant in comparison.

  • 33.
    Potrivitu, George-Cristian
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. University Toulouse III Paul Sabatier France.
    Low–voltage External Discharge Plasma Thruster and Hollow Cathodes Plasma Plume Diagnostics Utilising Electrostatic Probes and Retarding Potential Analyser2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The present thesis is the result of a research period at the Institute of Space and Astronautical Science of the Japanese Aerospace Exploration Agency, ISAS/JAXA within Funaki Laboratory of the Department of Space Flight Systems that followed the path of plume plasma diagnostics for space electric propulsion drives. During the experimental studies two high-current hollow cathodes and an innovative prototype of a low-voltage fully external discharge plasma thruster (XPT) had their plasma plumes diagnosed using electrostatic probes and retarding potential analyser (RPA).

    A Hall thruster and hollow cathode plume is defined as an unmagnetised quasi-neutral plasma which is mainly formed of neutral particles, electrons, singly and doubly charged ions. Plasma diagnostic techniques provide information through practical observations in order to fully understand the dynamics of the aforementioned plume components, the physical processes taking place within the plume and their effects on the spacecraft, for instance. Mastering these aspects of the plasma plume of space electric propulsion drives bolster the design processes, leading to highly efficient devices.

    Firstly, the introduction provides insights on the fundamental principles of hollow cathodes and Hall thrusters and a brief presentation of the plasma diagnostic techniques used during the research: single and double Langmuir probes, emissive probes and retarding potential analyser. Then, the fundamental plume diagnostics principles are depicted in an exhaustive way, departing from classical plasma kinetic theory, energy distribution functions and ending with an overview on the theory of charge collection by cylindrical probes. Subsequently, peculiarities of various analysis techniques are exposed for the Langmuir probes, emissive probes and RPA, with an emphasis on their strengths and demerits.

    The experimental setups for the cathodes and XPT plume diagnostic procedures are then outlined. The experimental logic, setup and electrical diagrams as well as a presentation of each probe design and manufacturing details are extensively discussed.

    The hollow cathodes experimental results are exposed with a discourse that aims of overviewing the difference between the various data analysis methods applied for the raw data. A discussion ensued based on the results in order to effectively identify mechanisms that produced the observed plasma parameters distributions.

    For the first time, the plume of a fully external discharge plasma thruster was diagnosed utilising double Langmuir probes.  The thesis highlights the main results obtained for the XPT far-field plume plasma diagnostics. The experimental findings for both thruster centreline positions and 2D plume maps for several axial distances away from the anode plate offer a ground basis for future measurements, a comparison term and a database to support ongoing computational codes. The results are discussed and related to the thruster performances data obtained during previous experiments.

    The thesis includes consistency analyses between the experimental data and the numerical simulation results and the uncertainties in measured plasma parameters associated with each data analysis procedure are evaluated for each data set. Last, the conclusions underline the main aspects of the research and further work on the previously mentioned plasma diagnostic techniques for hollow cathodes and XPT is suggested. 

  • 34.
    Rijal, Samundra
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Case Study: Conceptual Ground Station Design for N66 Connect AB2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As the communication deficit in the Arctic region is enormous especially above 75 [Deg] N latitude, the concern and opportunity of providing reliable & efficient connectivity in the Arctic region has beenduly noted & understood by N66 Connect AB (N66). This case study documents a comprehensive research which implements system engineering approach for establishment of a Ground Station (GS) at Svalbard, Norway with sole focus of connecting the inaccessible geographical region lying in the Arctic with rest of the world. Several GS system & subsystem are studied and comparative analysis is made on how the communication can be established with the N66 Connect AB (N66)’s potential clients and its satellites that are to be deployed in September, 2018.The case study resulted in analysis of several risks involved during development & operation of the GS,the hardware, software & operational architecture, the features of GS’s system capable of meeting N66’s objectives and the market potential of the service after GS operations.

  • 35.
    Shaik Fareedh, Junaidh
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Design, Fabrication and Modelling of Three Axis Floating Satellite Simulator2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Floating Satellite (FloatSat) system project which has been developed at the ‘Department of Aerospace Information Technology - University of Würzburg’ is used to test, develop and implement various attitude control algorithms and strategies for small satellites [1]. The FloatSat project is designed to operate on a Frictionless air bearing surface that works with compressed air flowing distributed on a hemisphere. This hemisphere is used to replicate the space environment required for a satellite to perform its attitude control, solar panel deployment and payload mission, the FloatSat basically consist of 1 axis control and stabilization with reaction wheel. Taking FloatSat to the next level, the aim of the Thesis is to Design, Fabricate and Model a three-axis controllable FloatSat that can be contained in a Sphere for free rotation and movement. The best feature of FloatSat is that they are plug & play, easily accessible and compact size; retaining all these features in the design and extending the functionality of the product proves to be challenging. Furthermore, in the thesis it will be explained in detail about the various design consideration and selection of most feasible method on producing the final product. After the preliminary research for the design characteristics it was clear that the new FloatSat will be equipped with a controllable center of gravity mechanism that will provide balancing in any desired orientation. To obtain this feature three controllable moving masses are to be used in each axis of reaction wheel position. With Three reaction wheels and three moving masses to be equipped in the FloatSat the design challenges were high as considering the Sphere diameter is only 198mm.

    The various successful 3 axis satellite simulators are either huge or they are constrained in any one of the axis where it is positioned. On doing literature research it became clear that the sphere configuration with the given size has never been documented with promising results. It makes this thesis work to be first of its kind to perform 3 Axis FloatSat stabilization in a sphere of 198mm diameter. The FloatSat components include microcontroller STM32F4, Wi-Fi module for communication, three reaction wheel motors, three axial moving mass motor, Lithium Polymer batteries and motor controllers. 

  • 36.
    Siderud, Emelie
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Upgrading a groundbased 142 GHz microwave radiometer to higher sensitivity2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The accuracy of ozone measurements in the middle atmosphere is of great importance when determining its diurnal variation. A high time resolution of the measured data is desirable and depends on the sensitivity of the receiver used to detect the ozone. This thesis aims to improve the sensitivity of a groundbased 142 GHz microwave radiometer used for measuring atmospheric ozone data. This is done by replacing the previous receiver components with a series of new components and arranging them in different setups for comparison purposes. Mechanics and wiring were changed in order to install the setups along with changes in the optics. Each test setup could be implemented as a first step towards improving the sensitivity of the radiometer. The result show that the optics contribute with an unexpected addition of noise to the measurements and hence the overall performance and improvement of the radiometer could not be determined. Suggestions are made for further work which include improving the optics and performing cryo-measurements.

  • 37.
    Tariq, Usama
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Robotic Grasping of Large Objects for Collaborative Manipulation2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In near future, robots are envisioned to work alongside humans in professional anddomestic environments without significant restructuring of workspace. Roboticsystems in such setups must be adept at observation, analysis and rational de-cision making. To coexist in an environment, humans and robots will need tointeract and cooperate for multiple tasks. A fundamental such task is the manip-ulation of large objects in work environments which requires cooperation betweenmultiple manipulating agents for load sharing. Collaborative manipulation hasbeen studied in the literature with the focus on multi-agent planning and controlstrategies. However, for a collaborative manipulation task, grasp planning alsoplays a pivotal role in cooperation and task completion.In this work, a novel approach is proposed for collaborative grasping and manipu-lation of large unknown objects. The manipulation task was defined as a sequenceof poses and expected external wrench acting on the target object. In a two-agentmanipulation task, the proposed approach selects a grasp for the second agentafter observing the grasp location of the first agent. The solution is computed ina way that it minimizes the grasp wrenches by load sharing between both agents.To verify the proposed methodology, an online system for human-robot manipu-lation of unknown objects was developed. The system utilized depth informationfrom a fixed Kinect sensor for perception and decision making for a human-robotcollaborative lift-up. Experiments with multiple objects substantiated that theproposed method results in an optimal load sharing despite limited informationand partial observability.

  • 38.
    Tiainen, Arttu
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Inter-Satellite Link Antennas: Review and The Near Future2017Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    The emerging trend in distributed spacecraft systems of using multiple spacecraft which share functions as opposed to independent spacecraft has given opportunities for missions previously infeasible. Inter-satellite link (ISL) communications provide a direct link within the space segment without need of an intermediate ground segment to relay the data. As the distributed spacecraft systems (DSS) have become less exotic and more complex, the need and demand for inter-satellite antenna systems has increased and the requirements for the antenna systems more diverse and become more demanding. This document is a research of the antennas currently used for ISL, already flown or will be launched in the near future. While the emphasis is strongly in the antennas, the other parts of the ISL communications sub-systems are observed. To limit the scope of the work, optical cross links are not observed in this document. ISL used only for very close proximity, such as several kilometres, are given only limited scope as the main challenges on those do not involve antennas. Furthermore, the major emphasis is given to systems which can be seen as commercially important. This document is divided in five main sections and the conclusions. In the first section the features and the challenges of ISLs are described. In the second section a parametrisation system for antennas is defined and this system is used in following sections to describe the ISL sub-systems and antenna used in them. The third part is a survey of recently flown space missions with ISLs. The fourth section is a survey on the missions which are scheduled to fly in near future and a brief survey of the solutions offered by satellite service providers and manufacturers. Due to the limited technical data available, the fourth section contains far more reverse engineering and assumptions than the survey on legacy missions. The fifth section describes the several families of ISL suitable antennas under development and discusses about several topics which relate to the ISL antenna development. In this part also are defined several example antenna specifications and the applications of those. The study concludes that antennas suitable for inter-satellite links are not inherently different from ground segment communication antennas of the S/C. The major difference is the need for greater coverage, which can be attained by multiple antenna elements, beam steering or antenna pointing. Specific considerations are needed to be taken into account and often the use of ISLs will increase the technical challenges, but it can provide solutions for problems which cannot be solved otherwise.

  • 39.
    Vakkada Ramachandran, Abhilash
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Design and Testing of Thermal Chambers for Space Qualification and Planetary Protection2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 40.
    Villlalba Corbacho, Víctor Manuel
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Cranfield University.
    Vibro-acoustic monitoring for in-flight spacecraft2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The concept of using the vibration transmitted through the structure of space systems whilst they are in flight for monitoring purposes is proposed and analysed.The performed patent review seems to indicate that this technique is not currently used despite being, in principle, a good way to obtain valuable knowledge about the spacecraft’s condition. Potential sources of vibration were listed and some of them were down-selected via a trade-off analysis for implementation in a numerical model of a CubeSat structure. Models were proposed for the sources chosen and implemented in the Ansys Workbench software, along with a simplified structure designed to be representative of a generic picosatellite mission.The results confirmed very different amplitude and frequency ranges for the sources of interest, which would make it difficult to monitor them with one type of sensor.Basic system requirements for accelerometer operating under space conditions were derived and commercial sources were identified as already having the technologies needed.The conclusion was a positive evaluation of the overall concept, although revising negatively the initial expectations for its performance due to the diversity encountered in the sources.

  • 41.
    Walden, Aleksi
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    SMOS satellite hardware anomaly prediction methods based on Earth radiation environment data sets2016Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    SMOS (Soil Moisture and Ocean Salinity) is ESA's Earth Explorer series satellite carrying the novel MIRAS (Microwave Imaging Radiometer with Aperture Synthesis) interferometric synthetic aperture radar. Its objective is monitoring and studying the planet's water cycle by following the changes in soil moisture levels and ocean surface salt concentrations on a global scale. The success of the mission calls for nearly uninterrupted operation of the science payload. However, the instrument experiences sporadically problems with its hardware, which cause losses of scientific data and may require intervention from ground to resolve. The geographical areas in which most of these anomalies occur, polar regions and the South-Atlantic anomaly, give cause to assume these problems are caused by charged particles in the planet's ionosphere. In this thesis, methods of predicting occurrence of hardware anomalies from indicators of Earth radiation environment are investigated.

  • 42.
    Zamouril, Jakub
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Flight Software Development for Demise Observation Capsule2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This work describes the process of the design of a flight software for a space-qualified device, outlines the development and testing of the SW, and provides a description of the final product. The flight software described in this work has been developed for the project Demise Observation Capsule (DOC). DOC is a device planned to be attached to an upper stage of a launch vehicle and observe its demise during atmospheric re-entry at the end of its mission. Due to constraint on communication time during the mission and the need to maximize the amount of transferred data, a custom communication protocol has been developed.

1 - 42 of 42
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf